The present invention pertains to a device for transferring continuously transported printing products, e.g., book blocks, books or sheet stacks consisting of folded and/or non-folded sheets, from an essentially flat lying position into an upright position or vice versa by means of a conveyor that is twisted about a longitudinal axis.
Transfers of the aforementioned type take place at various points in the process chain for manufacturing books. For example, the sheet stacks formed from loosely gathered folded sheets on a gathering conveyor of a gathering machine are transferred from their essentially flat lying position into an upright position with the spine pointing downward such that they can be delivered to the infeed system of an adhesive binder. With continuously transported printing products, the uprighting takes place at the delivery end of the gathering conveyor that is composed of a transport channel and a transport chain with pushers that advance the sheet stacks on the transport channel, wherein the transport channel with its channel side plates is progressively twisted about a longitudinal axis in order to upright the sheet stacks. In the uprighting region, the transport channel consists of pattern-rolled channel side plates with air blast nozzles recessed therein. Despite these measures for minimizing the friction in the uprighting channel, the bottom sheets lying on the channel side plates may still shift relative to the sheets of the stack lying thereon, particularly when processing individual sheets or extremely thin paper types.
DE 29 43 260 A1 discloses a device for transferring books from a vertically standing position into a horizontally lying position by utilizing two perpendicularly arranged roller conveyors with rotatively driven rollers, wherein each roller conveyor is twisted about a longitudinal axis. Steadying rods extend parallel to and are spaced apart from the vertically standing rollers of one roller conveyor, namely from the delivery end of the roller conveyor up to the transition region of the rollers from the vertical position into the horizontal position, so as to prevent the books being delivered from opening before they are laid down. There also exist lying-down devices with two driven plate chain conveyors that are arranged perpendicular to one another and respectively twisted by 90° along a longitudinal axis. The individual transport rollers and support plates of these two known lying-down devices respectively provide the products to be transferred with a linear support surface that is oriented transverse to the transport direction. Due to the respectively twisted arrangement of the transport rollers and support plates, printing products, particularly less flexible printing products, only lie partially on the transport means. The thusly caused transport conditions are associated with a certain slip and do not allow a positionally accurate and cyclically synchronous transport, particularly during start-up and stopping processes, such that an additional cyclic infeed of the books into downstream machines is required. In addition, the transport devices are only suitable for the uprighting of products to a limited degree. In the device known from DE 29 43 260 A1, a certain flexing effect of sheets that are loosely stacked on top of one another can also be observed. This means that lower sheets may shift rearward relative to sheets lying thereon.
It is also known to realize the lying down and uprighting by means of twisted clamping belt conveyors with belts that are respectively placed around two deflection rollers and jointly twisted by 90° between the deflection rollers. DE 30 06 266 A1 discloses a clamping belt conveyor that is twisted by 180° and used as a turning device for reversing continuously transported printing products by 180°. These known clamping belt conveyors have a complicated design because several different types of guide means are required for achieving a satisfactory guidance of the twisted transport belts. In addition, and is impossible to prevent relative movements between the transport belts that, in turn, cause the sheets in the stack or the individual parts of freshly bound book blocks to shift.